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        <h1>HDU-5670 Machine</h1>
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          <time>2016年04月28日</time>
          
          | <i class="fa fa-folder-open-o" aria-hidden="true"></i> 
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        <h1 id="题目："><a href="#题目：" class="headerlink" title="题目："></a>题目：</h1><p>Machine Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 543 Accepted Submission(s): 313</p>
<p>Problem Description There is a machine with m(2≤m≤30) coloured bulbs and a button.When the button is pushed, the rightmost bulb changes. For any changed bulb,</p>
<p>if it is red now it will be green;</p>
<p>if it is green now it will be blue;</p>
<p>if it is blue now it will be red and the bulb that on the left(if it exists) will change too.</p>
<p>Initally all the bulbs are red. What colour are the bulbs after the button be pushed n(1≤n&lt;263) times?</p>
<p>Input There are multiple test cases. The first line of input contains an integer T(1≤T≤15) indicating the number of test cases. For each test case:</p>
<p>The only line contains two integers m(2≤m≤30) and n(1≤n&lt;263).</p>
<p>Output For each test case, output the colour of m bulbs from left to right. R indicates red. G indicates green. B indicates blue.</p>
<p>Sample Input</p>
<p>2 3 1 2 3</p>
<p>Sample Output</p>
<p>RRG GR</p>
<h1 id="代码："><a href="#代码：" class="headerlink" title="代码："></a>代码：</h1><figure class="highlight c++"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// oj.cpp : 定义控制台应用程序的入口点。</span></span><br><span class="line"><span class="comment">//</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">char</span> <span class="title">out</span><span class="params">(<span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> a)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">switch</span> (a%<span class="number">3</span>)</span><br><span class="line">    &#123;</span><br><span class="line">    <span class="keyword">case</span> <span class="number">0</span>:</span><br><span class="line">        <span class="keyword">return</span> <span class="string">'R'</span>;</span><br><span class="line">    <span class="keyword">case</span> <span class="number">1</span>:</span><br><span class="line">        <span class="keyword">return</span> <span class="string">'G'</span>;</span><br><span class="line">    <span class="keyword">case</span> <span class="number">2</span>:</span><br><span class="line">        <span class="keyword">return</span> <span class="string">'B'</span>;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="title">mypow</span><span class="params">(<span class="keyword">unsigned</span> <span class="keyword">int</span> a, <span class="keyword">unsigned</span> <span class="keyword">int</span> b)</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> r = <span class="number">1</span>;</span><br><span class="line">    <span class="keyword">while</span> (b--)</span><br><span class="line">    &#123;</span><br><span class="line">        r *= a;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">return</span> r;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    ios::sync_with_stdio(<span class="literal">false</span>);</span><br><span class="line">    <span class="built_in">cin</span>.tie(<span class="literal">NULL</span>);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">int</span> T;</span><br><span class="line">    <span class="built_in">cin</span> &gt;&gt; T;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">while</span> (T--)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> n;</span><br><span class="line">        <span class="keyword">unsigned</span> <span class="keyword">int</span> m;</span><br><span class="line">        <span class="built_in">cin</span> &gt;&gt; m &gt;&gt; n;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">for</span> (<span class="keyword">unsigned</span> <span class="keyword">int</span> i = <span class="number">1</span>;i &lt;= m;++i)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> r = mypow(<span class="number">3</span>, m - i);</span><br><span class="line">            <span class="built_in">cout</span> &lt;&lt; out(n / r);</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="built_in">cout</span> &lt;&lt; <span class="built_in">endl</span>;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h1 id="解析-amp-吐槽："><a href="#解析-amp-吐槽：" class="headerlink" title="解析&amp;吐槽："></a>解析&amp;吐槽：</h1><p>一道水题。注意最右边的灯泡是按一下按钮改变一次，从右边数第二个灯泡是按 3 下按钮改变一次，第三个是 9 下按钮。因此第 n 个就是按 3^(n-1)个按钮改变一次了。 本题的幂运算需要自己写函数，cmath 自带的 pow 没法返回 long long，会因精度损失而导致 wa。</p>

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        <ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#题目："><span class="toc-number">1.</span> <span class="toc-text">题目：</span></a></li><li class="toc-item toc-level-1"><a class="toc-link" href="#代码："><span class="toc-number">2.</span> <span class="toc-text">代码：</span></a></li><li class="toc-item toc-level-1"><a class="toc-link" href="#解析-amp-吐槽："><span class="toc-number">3.</span> <span class="toc-text">解析&amp;吐槽：</span></a></li></ol>
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